Estimating Caloric Expenditure Based on Center of Mass Motion and Heart Rate

Embodiments are disclosed for estimating caloric expenditure based on center of mass motion and heart rate. In an embodiment, a method comprises: obtaining acceleration and rotation rate of a wearable device worn on a limb of a user; transforming the acceleration and rotation rate into an inertial frame; determining a vertical component of acceleration, rotation rate magnitude and vertical component of rotational acceleration due to limb rotation; determining a work rate (WR) based caloric expenditure based on the vertical component of acceleration, rotation rate magnitude and a correlation coefficient that measures a correlation between the vertical component of acceleration and the vertical component of rotational acceleration; obtaining heart rate (HR) data from a heart rate sensor of the wearable device; determining an HR based caloric expenditure based on the HR data; and fusing, the WR based caloric expenditure with the HR based caloric expenditure to get a fused caloric expenditure.